Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 12~16

DOI : 10.9726/kspse.2015.19.5.012

Abstract

nanoparticle can be used for the improvement of performance of the epoxy resin composites. In this study, the effect of the size of nanoparticle on the mechanical properties for the epoxy resin composites was investigated. The size of nanoparticle was easily controlled by heat treatment. The heat treatment of nanoparticle was conducted between and . The obtained size of nanoparticle was 20 nm, 100 nm and 200 nm respectively. As the diameter of nanoparticle is smaller, the epoxy resin composite specimen showed higher tensile strength. It was also found that Vickers hardness of epoxy resin was increased by the addition of nanoparticle. But the size of nanoparticle did not strongly affected to the Vickers hardness of this material. The fracture surface of epoxy resin showed clear difference by the size of nanoparticlet.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 17~24

DOI : 10.9726/kspse.2015.19.5.017

Abstract

In this paper, the development of an air cushion transporter has been studied. To do this, theoretical analysis is introduced to design the equipment and computational fluid dynamics is also conducted. Design of an air cushion transporter for heavy load carriage is completed and a prototype is manufactured. Through the analysis and experiment of the developed the prototype, it can be known that the developed transporter can levitate the load of about 1 ton at the applied pressure of 0.2 MPa and the maximum lifting height at this condition is 17mm.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 25~31

DOI : 10.9726/kspse.2015.19.5.025

Abstract

This study deals with optimal conditions for design parameters of the multistage bollard with up and down installed on the street to protect pedestrians or stop cars. FE simulation and Taguchi method are used to achieve the optimization for the automatic multistage bollard to minimize effective stress caused by the external force. Thickness, height of stage 2, diameter and over-all height which affect its structural strength are chosen as design parameters. According to the experiments combined by orthogonal array, each of the effective stresses is evaluated. And the results are analyzed by using the signal to noise ratio concept of Taguchi method. From their results, the optimal combination of design parameters are proposed.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 32~37

DOI : 10.9726/kspse.2015.19.5.032

Abstract

The present study is to investigates the convective heat transfer characteristics and pressure drop inside the rib-roughened cooling passage of gas turbine blades. The divergent rectangular channel is fabricated with V-shaped ribs on one wall only and the inlet hydraulic diameter to outlet hydraulic diameter ratio() of 1.49 is used. The current investigation has covered a Reynolds number (Re) range of 22,000~75,000, relative roughness height () of 0.1~0.2, and rib angle of attack (a) of , , and for a fixed relative pitch of 10. Results show that the Nusselt numbers are the greatest in the -angled ribs; however, the total friction factors are the highest in the -angled ribs.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 38~44

DOI : 10.9726/kspse.2015.19.5.038

Abstract

The cold-rolled steel sheet for automobile is liable to corrosion, and will be painting in a variety of ways for the anticorrosive. This paper was coated on cold rolled steel (SPCC and SPFC590) for automobiles using five kinds of organic/inorganic hybrid solution. This was evaluated corrosion resistance and so on by the salt spray. Corrosion area was less according to increasing of curing time in 2 types of steel plate with 5 types of the coating solution. No.1 solution was showed the best corrosion resistance regardless of the kinds of the steel sheet. It is judged that the melamin hardner had the role of bridge between polysilicate and urethan resin. Other properties were excellent in all solution.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 45~51

DOI : 10.9726/kspse.2015.19.5.045

Abstract

Grade 91 steel is used for the major structural components of Generation-IV reactor systems such as a very high temperature reactor (VHTR) and sodium-cooled fast reactor (SFR). Since these structures are designed for up to 60 years at elevated temperatures, the prediction of long-term creep life is very important to determine an allowable design stress of elevated temperature structural component. In this study, a large body of creep rupture data was collected through world-wide literature surveys, and using these data, the long-term creep life was predicted in terms of three methods: Larson-Miller (L-M), Manson-Haferd (M-H) and Wilshire methods. The results for each method was compared using the standard deviation of error. The L-M method was overestimated in the longer time of a low stress. The Wilshire method was superior agreement in the long-term life prediction to the L-M and M-H methods.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 52~59

DOI : 10.9726/kspse.2015.19.5.052

Abstract

This paper is presented for the free vibration of a conical shell with annular plates or circular plate using the transfer of influence coefficient. The governing equations of vibration of a conical shell, including annular plate, are written as a coupled set of first order differential equations by using the transfer matrix of the shell. Once the transfer matrix of a single component has been determined, the entire structure matrix is obtained by the product of each component matrix and the joining matrix. The natural frequencies and the modes of vibration were calculated numerically for joined conical-annular plates. The validity of the present method is demonstrated through simple numerical examples, and through comparison with the results of finite element method, transfer matrix method and ANSYS. The conclusion show that the present method can accurately obtain natural vibration characteristics of the conical shell with annular or circle end plates.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 60~66

DOI : 10.9726/kspse.2015.19.5.060

Abstract

Embrittlement of material by hydrogen charging should be cleared for safety of storage vessel of hydrogen and components deal with hydrogen. A stainless steel is generally used as materials for hydrogen transportation and storage, and it has a big advantage of corrosion resistance due to nickel component in material. In this study, microscopic damage behavior of stainless steel according to the hydrogen charging time using nondestructive evaluation was studied. The surface of stainless steel became more brittle as the hydrogen charging time increased. The parameters of nondestructive evaluation were also changed with the embrittlement of stainless steel surface by hydrogen charging. Ultrasonic test, which is the most generalized nondestructive technique, was applied to evaluate the relationship between the ultrasonic wave and mechanical properties of stainless steel by hydrogen charging. The attenuation coefficient of ultrasonic wave was increased with hydrogen charging time because of surface embrittlement of stainless steel. In addition, acoustic emission test was also used to study the dynamic behavior of stainless steel experienced hydrogen charging. AE event at the hydrogen charged specimen was obviously decreased at the plastic zone of stress-strain curves, while the number of event for the specimen of hydrogen free was dramatically generated when compared with the specimens underwent hydrogen charging.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 67~72

DOI : 10.9726/kspse.2015.19.5.067

Abstract

The reliable operation of onsite emergency diesel generator(EDG) should be ensured by a conditioning monitoring system designed to maintain, monitor and forecast the reliability level of diesel generator. The purpose of this paper is to develop condition diagnosis algorithm(logic) and analysis program of engine for the accurate diagnosis in actual condition of emergency diesel generator engine. As a result of this study, we confirmed that developed engine condition diagnosis algorithm and analysis program could be efficiently applied for actual EDG engine in nuclear power plant.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 73~79

DOI : 10.9726/kspse.2015.19.5.073

Abstract

The effects of hydrogen charging on the mechanical properties of 304 stainless steels were investigated in conjunction with the detailed examinations of their fracture modes. The dependence of the absorbed impact energy and the surface hardness of the 304 stainless steels on the hydrogen charging time was characterized. The tensile properties of the 304 stainless steels by the variation of cross-head speed were also evaluated at the room temperature. The hydrogen charging was performed by an electrolysis method for all specimens of the 304 stainless steels. The mechanical properties of the 304 stainless steels exhibited the sensitivity of embrittlement due to a hydrogen charging. The correlation between mechanical properties and fracture surfaces was discussed.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 80~85

DOI : 10.9726/kspse.2015.19.5.080

Abstract

The unsteady-state, incompressible and three-dimensional large eddy simulation(LES) was carried out to analyze the structure of turbulent flow fields according to the operating loads of three-dimensional small-size axial fan(SSAF). LES shows the best prediction performance in comparison with any other Reynolds averaged Navier-Stokes(RANS) method because static pressure coefficients analysed by LES show a little bit larger than measurements including all flow coefficients. Also, it can be known that the wake of SSAF is divided into from axial flow to radial flow before and behind stall region according to the increase of static pressure through LES analysis.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 86~92

DOI : 10.9726/kspse.2015.19.5.086

Abstract

p-DCPD were prepared by in-suit ROMP polymerization using and . The results showed that mole ratio of 1:2.0:350 had the curing-time of 60sec and crosslinking degree of 90.44%. The curing time of DCPD polymerization by was shortened, and monomer conversion and crosslinking degree were decreased with temperature and the number of moles of and . and is damaged its function by the reaction with the air in the atmosphere and did`t proceed the polymerization properly.

Journal of the Korea Society For Power System Engineering, volume 19, issue 5, 2015, Pages 93~98

DOI : 10.9726/kspse.2015.19.5.093

Abstract

Nuclear power plants has a number of valves, which are operating at a high temperature-high pressure and radiation environment conditions. Nevertheless, it is important to maintain the reliability of the valves to ensure safe operation of the nuclear power plant. However, the aging of the valves by increasing of years of plant operation and the system transients due to the sudden load change are working the failures of the reliability of the valve. In this paper, we evaluate experimentally the performance change according to the thermal aging of the valve. Results show that the valve stem and the actuator leakages were enlarged by the thermal aging.